On Biofuels, part 3: The future of bioenergy

In the first installment of this series we explored the basic facts about electricity production from biomass, and some pervasive myths about it. In the second, we delved into the complicated issues involved in accounting for the climate implications of biopower. In this installment, Ben Paulos explores the future of biopower.

Electricity is just one possible use for biomass feedstocks. There are many energy products – ethanol, biodiesel, methane, heat, and more – let alone all the other uses of plants that we have devised over the millennia.

Given the many competing options for a limited supply of biomass, does biopower even have a future? And given the many other ways of producing low-carbon energy, do we need it to solve global warming?

Niches

Forecasts about bioenergy from energy agencies and analysts have been all over the map, some predicting vast potential and others seeing insurmountable barriers to growth. As mentioned in our first installment, the US Energy Information Administration (EIA) has been steadily ramping down expected growth for biopower.

While the models may be uncertain, there are some basic principals that will likely guide bioenergy’s role in the future, and certain niches that it will likely fill.

Germany, always a bellwether for the future of energy, has largely lost hope in bioenergy as a significant source of new renewable energy. Rainer Baake, state secretary in charge of the German energy transition, has concluded that wind and solar are the “clear winners” and that bioenergy has a limited future. Germany has been lowering goals and incentives for bioenergy over recent years.

The rise of wind and solar, combined with their vast resource potential, has created a significant impediment to the growth of biopower world wide. At the same time, this may have helped to ratchet down expectations that biopower could never have achieved anyway.

The use of bioenergy feedstocks will gravitate toward the highest value markets where it doesn’t have to compete with wind and solar for electricity production, or against food, wood products, and wildlife for space.

CHP and district energy: Biomass can be very valuable when it supplies combined heat and power (CHP) systems, especially those connected to district heating and cooling systems. In this high-efficiency application, maximum value is wrung from the feedstocks. District energy systems can integrate well with wind and solar to provide long term thermal storage.

Heat: Humans have been turning biomass into heat since the invention of fire. Only recently has it been displaced by fossil fuels, and only partly displaced in some parts of the world. But in a carbon constrained future we will need low-carbon heat sources, not fossil heat. Wind and solar electricity can power heat pumps, which could compete with biomass, but may not correlate with periods of heating and cooling demand, requiring greater amounts of storage.

Grid balancing: Even with large amounts of wind and solar, we will still need dispatchable resources to balance the grid, like energy storage, flexible demand, and low carbon generation. Biopower, especially in gasification systems (BIGCC), could be a flexible and efficient balancing source, and fill in during off-season lulls in wind and sunshine.

Jet fuels: Some experts feel that in the long run we will need to use all available bioenergy feedstocks for air travel, since batteries may never have sufficient energy density to fly long distance. Air travel currently accounts for two percent of total carbon emissions. Airlines are researching low carbon fuels, and have recently agreed to offset any emissions above 2020 levels.

Limits to growth

Bioenergy will be limited by constraints, conflicts, and competition.

As bioenergy scales up to be a significant energy supplier, it encounters increasing conflict, and ultimately hits hard limits. Other buyers of biomass feedstocks, like food, clothing, buildings, and paper, can pay more for feedstocks than energy can. According to the National Renewable Energy Lab, food accounts for 62 percent of the 6 billion metric tons of biomass used each year, while wood products make up most of the rest.

Bioenergy also encounters land use limitations, due to conflicts over food production and natural habitats and forests. There is only so much biomass waste and so many unused “degraded” lands that it can be sourced from. Wildlife proponents rightly fear that a runaway bioenergy industry would increase pressure on wild lands, especially in countries with weak protections.

Any biomass that is used for energy must be used with maximum efficiency. While utilities often try to convert old inefficient coal plants to biomass, that approach wastes too much precious biomass and creates gnarly logistical problems. The ideal biomass plant produces both heat and power, has scrubbers to catch particulates, and draws from a sustainable and local feedstock supply.

The best example of the wrong way to do biopower is the massive Drax plant in the UK, a 4000 MW set of coal burners that is converting to biomass. It does not use the heat it produces because it is too large, wasting much of the energy in the wood pellets that it imports from the US and Canada.

The right way is the many college campuses in the US that have been replacing coal in their district heating and cooling systems with sustainably sourced local biomass. Middlebury College in Vermont became the first major college campus to achieve carbon neutrality in 2016, thanks in large part to their biomass energy system. The plant was launched in 2009 with a speech by Middlebury scholar Bill McKibben, noted environmentalist and founder of 350.org.

Other limitations will strike earlier, as bioenergy runs into competitive limits. Wind and solar are cheaper and more scalable ways to make low-carbon electricity. Fossil fuels can be decarbonized, given a high enough carbon price. Improvements in electric vehicles raise doubts about the need for ethanol and biodiesel, at least for use in light-duty vehicles.

Negative Carbon

One option that could encourage greater use of bioenergy is if it can be combined with carbon capture and sequestration (CCS), to become a negative carbon source.

CCS has usually been considered a solution to the carbon problems from coal, to make a truly “clean coal.” But it can be applied to any carbon source. While coal CCS takes old carbon from underground and returns it, biomass CCS (known as BECCS) stores carbon recently taken from the atmosphere by plants.

Biomass can be gasified, for example, where volatile gases are extracted and burned in a power plant, used as a transportation fuel, as a chemical feedstock, or as a fertilizer. If the carbon is separated out in this process, leaving hydrogen as the energy carrier, the carbon can then be stored, or even used as a feedstock in its own right.

A real world example of BECCS is the ADM ethanol plant in Decatur, Illinois. With DOE funding, ADM is sequestering CO2 from the fermentation process in sandstone formations deep under ground, thus making low-carbon ethanol.

Scientists working on the UN Intergovernmental Panel on Climate Change (IPCC) have portrayed scenarios that rely heavily on BECCS to reduce atmospheric carbon to limit warming to 2˚ C. In the fifth assessment report, released in 2014, BECSS and other carbon-removing technologies were seen as a necessary “savior” to reducing carbon after 2050.

Conclusion

The public discourse on biopower is polarized and often highly emotional. For some, biopower is tied to the love of forests and trees, the birthplace of environmental awareness, predating modern movements and concepts. Biopower is part of the long-running battle between forest conservation advocates and the owners and loggers of working forests.

Given the entrenched positions of both sides, it can be hard to identify a common ground. This series was intended not to advocate for or against biopower, but to shed light on its complexity.

The ironies of biopower – that we can cut down trees to save the planet – make it attractive fodder for reporters. But reporters are often led astray by the side with the most vivid story, rather than by the facts on the ground.

And little surprise—those facts are muddy. The future of bioenergy is uncertain. The many constraints it faces suggest it could see very little growth. But the huge challenge of solving climate change makes some think it could be the savior of the planet in the long run.

If bioenergy is to expand without creating more threats to wildlife, we will need new ways of managing wild lands that solve for both resource extraction and habitat protection. We will need a global change in diet, to free up the massive amount of land and resources devoted to beef production. And we will need to direct the limited biomass resources we have to their highest value applications, and with greater efficiency.

Most of all, we will need a rational and clear understanding of the constraints, the barriers, and the pitfalls of bioenergy – as well as the potential and the benefits.

Bentham Paulos is an energy consultant and writer based in California. His views are his own, and don’t necessarily represent those of any of his clients.

2 Comments

I probably agree with most of this but it is somewhat difficult to read because it is so general, giving very limited feeling for the quantities involved. Maybe what is needed is a part IV with references to some reviews of studies which attempt to work through the numbers for some specific cases, if these exist.